IMF Lab report - Grade: A PDF

Preview

Summary

Lab...

Description

19. For each liquid, subtract the minimum temperature from the maximum temperature to determine ΔT, the temperature change during evaporation. 20. Based on the ΔT values you obtained for these two substances, plus information in the Pre -Lab exercise, predict the relative size of the ΔT value for the remaining substances (listed in Table 2) and explain how you arrived at this answer in the space provided. Compare its hydrogen-bonding capability and molecular weight to those of ethanol and 1-propanol. It is not important that you predict the exact ΔT value; simply estimate a logical value that is higher, lower, or between the previous ΔT values (for example, > 4°C or < 8°C will suffice). 21. The remainder of the experiment you will test your predictions in Step 20 and record the temperature change during evaporation for the remaining substances (listed in Table 2) by repeating Steps 11-19.

Data and R Results esults Table 1: Temperature change during evaporation

Substance

Tmax (°C)

Tmin (°C)

ΔT (°C) Tmax- Tmin

Ethanol 1-Propanol

Table 2: Comparing and predicting temperature changes during evaporation

Substance

Methanol

1-Butanol

Pentane

Hexane

Acetone

Water

Predicted ΔT (⁰C)

Explanation

Tmax (°C)

Tmin (°C)

ΔT (°C) Tmax- Tmin

1. Using Excel, plot a graph of ΔT (⁰C) values of the four alcohols versus their respective molecular weights. Plot molecular weight on the x-axis and ΔT on the y-axis. Label each point with the identity of the alcohol. Can you draw any conclusions regarding intermolecular forces and molecular weight from this graph? Discussion The following list was designed to help you construct a good discussion as well as to illustrate how you should go about analyzing the theory behind a particular experiment and relating it to the results and observations. For this experiment, consider and include in your discussion (but do not limit it to) the following: a. Correlate how readily a sample evaporated to the strength of the intermolecular forces in the molecule. b. Compare the following pairs of substances, which have nearly the same molecular weights but significantly different ΔT values, and explain this difference in terms of their intermolecular forces: i. 1-propanol and acetone ii. 1-butanol and pentane c. Compare the two alkanes in terms of structure, molecular weight and thus intermolecular forces. d. Compare the four alcohols in terms of structure, molecular weight and thus intermolecular forces Analyze the graph. Post-Lab Questions 1. In the space below, organize your samples from smallest ΔT to largest ΔT for your alkanes, and again for your alcohols: Alkanes: _____________________ < _____________________ Alcohols: _______________...